Legacy ImageMagick Discussions Archive

-grayscale rec709luminance was specially created to produce a linear equivalent of rec709luma so that there was some way to generate linear grayscale images. Same for -grayscale rec601luminance vs rec601luma. These are not really listed colorspaces but just argument names. The problem with the -gra...

I'm the OP of the discussion this apparently came out of. I'm not clear on whether this solves the colorspace problem. I wasn't aware that an image has a gamma property (how do I see it on the command line?), but this shouldn't be a substitute for setting a colorspace that accurately indicates what ...

But again, I do not think you can save that information in most image formats. So it would have to specially coded in the IM internal format and used only within a single command or saved to one of the IM formats such as MIFF or MPC or possibly PNG. That is a separate problem and won't be affected ...

Okay, so we agree that at least the output of -grayscale Rec709Luminance (and similar) in IM6 should automatically be labeled as some linear colorspace such as RGB (or ultimately something like LinearGray either now or in IM7). Would any maintainers or other care to comment in favor or against this?...

In what way would processing a "LinearGray" image differ from "RGB"? And how would processing "sRGBgray" differ from "sRGB"? In that case, we should label the result of "convert mysrgb.png -grayscale Rec709Luminance" as being in RGB colorspace (line...

As it stands in 6.8.7-0, IM doesn't seem to distinguish between linear and nonlinear gray colorspaces, i.e. there's no analogue to RGB vs sRGB for single-channel images. This causes problems. To avoid ambiguity with "Gray", I suggest that we add an explicitly-linear 1-channel colorspace ca...